Production of carbon black and apparatus therefor



July 7, 1931.

o; \SCHMIDT 51' AL PRODUCTION OF CARBON BLACK AND APPARATUS THEREFORFiled Sept. 4, 1929 Patented July 7, 1931 UNITED. STATES PATENT OFFICEOTTO SCHMIDT AND OTTO GROSSKINSKY, OF LUDWIG SEAFEN-ON-T HE-I RHINE,GERMANY, ASSIGNORS TO I. G. FARBENINDUSCD'RIE AKTIENGESELLSCHAFT, 0FFRANKFORT-ON-THE-MAIN, GERMANY, A CORPORATION OF GERMANY PRODUCTION OFGAB/B011 BLACK AND APPARATUS THEREFOR Application filed September 4,1929, Serial No. 390,367, and in Germany October 10, 1928.

This invention relates to improvements in and apparatus for themanufacture and production of carbon black.

We have found that a particularly finely divided carbon black isobtained by decomposing compounds of carbon in the gaseous or vaporousstate, in particular hydrocarbons, for example, unsaturatedhydrocarbons, such as acetylene, or allylene, or olefines or diolefines,such as ethylene, propylene, butylene, butadiene and the homologues ofthe said unsaturated hydrocarbons and also saturated hydrocarbons, suchas methane or ethane or even high hydrocarbons of the paraflin, aromaticor hydroaromatic series or mixtures of these substances, or carbonmonoxide, or carbon dioxide, or mixtures thereof with hydrocarbons withcatalysts and with the employment of an electric field in the presenceor absence of other gases or vapours, and at any suitable pressure. maybe atmospheric or reduced or elevated. If elevated pressures beemployed, usually those of about 10,20, 50, 100, 200 or even moreatmospheres are suitable.

Temperatures rangingbetween about 25 and 800 centigrade may be employedfor the process, and generally temperatures ranging between about 300and 500 centigrade furnish very good results, but temperaturesconsiderably above thesaid ranges may also be employed. If a relativelylow temperature is employed, a carbon black is ob.-

tained having an excellent covering power.

and blackness. Even higher temperatures for example temperatures between600 and 1000 centigrade may be employed particularly whenaromatic-hydrocarbons serve as 'the initial materials. Generallyspeaking,

higher temperatures are usually required for the production of carbonblack from saturated hydrocarbons than from unsaturated hydrocarbons.

As examples of other gases or vapours may be mentioned water vapour,nitrogen peroxide, carbon dioxide, nitrogen, hydrogen,

. which under the conditions of working employed does not have ahydrogenating action, methane, ethane and other lower hydrocarbons,which may, however, themselves be Thus, the pressure decomposed tocarbon black. The said other gases may be employed in molecular or anyother proportions with reference to the compounds of carbon to bedecomposed.

Catalysts having a dehydrogenating action are particularly advantageousfor the process according to the present invention, and in particularthose comprising metals of the iron group as such or in the form oftheir compounds, for example in the form of shavings, cuttings, ballsand the like, namely iron, nickel or cobalt, or compounds thereof,oxides in particular being very suitable. The metals of the iron groupobtained by the reduction of the corresponding oxides, nitrates,carbo'nates, hydroxides and the'like, are particu larly advantageous.The said catalytic materials may be employed. alone or as mixtures andtheir activity may be increased by the addition of activatingsubstances, in particular oxides, hydroxides, or carbonates ofthemselves may be added, or phosphorus pentoxide, if they are stableunder the conditions of working. The said additions may be employed insmall amounts, for example, up v to about 10 per cent, but often it willprove advantageous to employ ,larger amounts thereof, for example, agreater amount of the said additions than of the aforesaid metals fromthe iron group or the compounds thereof. T

- The aforesaid substances may also be employed on carriers, forexample, pumice, fire clay, silica gel, charcoal, magnesia, fullersearth and the like.

In accordance with the present invention the materials of which theelectrically charged electrodes are constructed, or which they comprise,which may consist, for example, of the metals, of the iron group, assuch or in the form of their compounds, for example, cobalt, nickel oriron, may themselves serve as catalysts. Thus, for example, the carbonsiderably deeper in colour than the carbon lack obtained withoutcharging the metal. his action may possibly be explained by asiming thatduring the reaction the carbon produced in the form of ions and thecomination of several particles of carbon to form rrger complexes isrendered difficult by the iarging of the catalyst, though this is onlyiggested by way of theory, and makes no ifl'erence in the actualpractice of the inven- .on.

Both continuous currents and alternating i-rrents may be employed in theprocess ac- )rding to this invention, and the currents re usually ofvery small magnitude, for ex- 'nple, of the order of 1 milliampere orbew, although, if desired, currents of higher r lower magnitude may beemployed. Thus, )1 example, with a voltage of 100, the elecrodes being 5centimetres apart, acurrent f about to 10' amperes is employed. hevoltage may be very low, for example, nly a few volts, but voltagesconsiderably igher may also prove advantageous, for exmple, of 200 voltsor even more.

The apparatus and electrodes employed ac- )rding to this invention maybe constructed if any suitable refractory material, for .ex-

mple, quartz, porcelain or metals. such as lumimum, copper or chromium,or alloys iereof, such as brass, or of alloy steels, or f zinc-plated,aluminium-plated, copperlated, or tin-plated iron.

The following examples will further illstrate the nature of theinvention, but the lvention is not restricted thereto, Examples and 3being explained with reference to 'igures 1 and 2, respectively, of theaccomanying drawings, which show arrangements E apparatus in verticalsection for carrying ut the process of the invention.

Ema'mple 1 In Figure 1 a nickel catalyst A, which is btained by thereduction of compressed ickel oxide at a temperature of 320 centirade,is placed in a vertically suspended 'ire cage B arranged round andelectrically )nnected with a tube C which is heated from 1e interior, bymeans of an electric resistance V eating .device D through which acurrent ows with a tension of 200 volts, which tube :rves as thepositive electrode. The said tube insulated by means of a mass F fromthe .short period of time a very finely divided carbon black collects onthe positive electrode, and this may be caused to fall oil by tapping orby interrupting or reversing the current. The decomposition of theethylene is practically quantitative. Thecarbon black thus obtainedpossesses an extraor? dinary fineness and blackness.

The ethylene may be replaced -by other olefines or carbon compounds.Instead of the pure gases, mixtures may also be employed, in particularmixtures with nitrogen, carbon dioxide, water vapour, methane, ethane,and the like. The tension may be varied within wide limits. The processmay also be carried out under diminished or increased pressure.

Eammple 2 A mixture is prepared from 96 per cent of cobalt oxide, and asmall addition say, 3 per cent of zinc oxide and 1 per cent of molybdicacid, and this is pressed and arranged to serve as a catalyst in ahorizontal tube of brass, where the said mixture is reduced in a currentof hydrogen at a temperature ot 320 centigrade. An electrode consistingof sheet aluminium insulated from the tube is arranged horizontallyabove the said catalyst. The said electrode is charged with a tension ofabout 80 "olts, the metal tube and at the same time the catalyst whichis in electrically conductive connection therewith is connected with thenegative pole of a battery and is at the same time earthed. If a mixtureof 1 part by volume of allylenehaving a boiling point of 23 ceutrigradebelow zero and of about 2 parts by volume of water vapour be passedthrough the tube at a temperature of between about 350 and 400Centigrade, a verygood yield of a carbon black of very high dispersityand having a deep black colour is obtained.

In place of water vapour gaseous hydrocarbons, such as methane, ethaneor ethylene may be employed as the extraneous gases or mixturesthereof." 1

Example 3 Referring to Figure 2 an aluminium boat D which serves as anelectrode is filled with a catalyst prepared from a mixture of 96 partsof cobaltoxide, 3 parts of zinc oxide and 1 part of thorium dioxidewhich has been reduced with hydrogen at a temperature of about 330Centigrade and is arranged in a horizontal quartz tube A. A counterelectrode E of aluminium sheeting is arranged horizontally above thesaid boat. D and isulated therefrom, the said counter electrom;

being connected with tl1e negative pole of a battery and with earth. 7The aluminium boat is charged to a tension of 80 volts and is connectedwith the positive pole of a. battery by means of the wire C. Electrodeand counter electrode are insulated by means of the .the gaseous phase,

stoppers B and B A mixture of 50 parts by volume of carbon monoxide, 10parts by volume of water va our and 40 parts by volume of nitrogen ispassed through the tube at a temperature of about 400 centigrade, acarbon black very deep in' colour being thus obtained. p

' E'aca/mLpZcJ I Propylene is passed under a pressure of 00 mm., atensionof 50 volts being employed, at a temperature of about" 400centigrade over a catalyst prepared by reduction of a "mixture of 97parts of cobalt oxide,

1 part of iron oxide and 2 parts of zinc oxide arranged in atube similarto that described in Example 3. In this manner a carbon black isobtained having a deep brownish-black colour.

Instead of working under reduced pressure atmospheric pressure orelevated pressure maybe employed. It the pressure be 'increased, it maybe especially advisable to employ the propylene in admixture withextraneous gases, this step being advantageous, since injurious--superheat1ngof thecarbon black is thereby avoided. That we claim is:

1. In the production of carbon black bydecomposition, by heat treatmentin the resenceof catalysts, of carbon compoun in the step of carryingout the said decomposition while maintaining the reaction zone under theaction of an electric field in the presence of water vapour;

2. A process for the production of carbon black, which comprises passingethylene, through a zone heated to a temperature of between aboyit 350and 400 C. and contain-V ing 'a catalyst prepared from cobalt oxide,with a small addition of zinc oxide and mobdioacidfjin which said zonean electric having field is set up by means of a current a tension ofabout 200 volts.

3. Apparatus for the production of carbon black by decomposition, byheat treatment in the; resence of catalysts, of carbon com pounds in-theearthed tube 0 ductive material, a further tube of refractory,electrically conductive material arranged concentrically in thesaidfirsttube, so as to leave a considerable space between the two' tubes, meansfor insulating the twp tubes fromone another, said second tube, acatalyst arranged within the space between the two tubes, means forconnecting the said second tube with-a source of electricity and meansfor passing the said compound 'of carbon in the gaseous phase throughthe said space between the two tubes.

OTTO SCHMIDT. OTTO GROSSKINSKY.

gaseous phase, comprising an I refractory, electrically cona heatingdevice v In testimony whereof we have hereunto set our hands.

